Or pus, or slime, or icky black stuff... If something's coming out of your eyes and it's not salty water then you can bet your bottom dollar that something pretty bad is happening to you. The trope comes in two flavours, which are, oddly, created to have the exact opposite effect on the audience:

Flavour one is designed to freak them out, and is usually a sign that the person has been infected by some horrible virus, or is being killed by weird supernatural means. Eye trauma is one of the easiest ways to gross people out, and this method has the added advantage that the person can be "cured" without having lost their vision permanently. Alternatively, it signifies that the "weeping" person is in some way inhuman - or at the very least a candidate for supervillainy and somewhat demonic entities and characters.

Flavour two, meanwhile, is used to signify someone's death in a poetic and possibly even "beautiful" way, especially if the character is a tragic villain. This is far less common, and the aim is not necessarily to freak out the audience but to add a layer of sadness to a death scene. Mopey vampires are particularly fond of this flavour. The undercurrent to this kind of bloody tears is that the person doing the crying is in some fundamental way (be it biologically or emotionally) incapable of doing so through normal means- but is so overcome with emotion that they are doing so anyway.

Along these lines, statuary or paintings doing this with the first flavour can mean someone present is utterly evil (if the items are holy relics) or that the item itself is an Artifact of Doom. With the second flavour, it means the item is a holy relic that's "manifesting" itself this way in response to some tragedy/holiness, whether of its own or those present.

Anime and Manga

When a Behelit summons the Godhand in the Berserk universe, its features rearrange into a human face, which sheds tears of blood and screams. This also happens to Griffith due to being tortured and Guts himself due to having his right eye clawed out by a demon.

The second flavor of this occurs in episode 25 of Cowboy Bebop, when Vicious kills the leaders of the Red Dragon and takes over the syndicate, executing one of them by slashing him across the eyes and making him "shed tears of scarlet."

In Chrono Crusade a statue of the Virgin Mary is seen crying tears of blood at one point.

Joshua also cries tears of blood when he first puts Chrono's horns on his head, and in the manga the Apostles cry tears of blood from the strain of a spiritual ceremony called the "oratorio."

It's more used for him to realize he's close to a Flicker, however. He initially relies solely on this to realize whe who he thinks is his sister, Runa, is really just a gun-toting Flicker named Asuka.

Naruto: Uchiha Itachi sheds tears of blood when he strains his sharingan to the limit while fighting his brother just before he dies at his brother's feet.

At Itachi's death his brother Sasuke, also cries blood tears from Itachi's blood that went into his eyes at the end of their fight.

Sasuke now exhibits the same behavior when he taxes his own Mangekyou Sharingan to a much greater degree.

Terry Bogard sheds a few when Sulia dies in Fatal Fury: the Motion Picture, and then attacks Mars.

Samurai Deeper Kyo averts Flavour two by having the Mibu cry tears of blood up until their death, when they can finally cry real tears.

In episode 3 of Shamanic Princess, Lena cried buckets of these when she overheated during her transformation

Alucard from Hellsing has cried tears of blood on occasion - once in a dream, remembering his defeat at the hands of Abraham van Helsing, and another at the time of Alexander Anderson's death.

Seras does this in the seventh OVA during a flashback of her horrific childhood where she was forced to watch as her mother's corpse was raped.

She does this in the last episode of the TV series as well.

In a rare variation that doesn't involve supernatural powers or symbolism, Mahou Sensei Negima has Negi bleeding out of his eyes after Jack Rakan beats the crap out of him, in addition to copious Blood From the Mouth. Given that earlier chapters of Negima went with Bloodless Carnage, it's simply an indicator of how badly injured he is.

Happened in D.Gray-man to Allen when he had to watch a bunch of Akuma getting destroyed by the "Third Exorcists." No wonder he objects to his bosses' methods...

This happens to Tsuchimikado in A Certain Magical Index when casting a huge spell despite being an esper. Also blood from the mouth and apparently rupturing blood vessels essentially everywhere. He gets better because said esper ability is a passive Healing Factor.

Another example in this series happens to Accelerator after watching how Yomikawa got stabbed and then crushed, by Kakine Teitoku, onto the floor many times despite Accelerator begging him to stop.

While not a real example, Ed from Fullmetal Alchemist has a tendency to look like he's doing this due to blood getting splashed on his face. This is apparently because the author likes to play around with the highlights and such created by a person crying but couldn't due to Ed's never crying being a plot point.

Sosuke in Full Metal Panic! after he learns of chidori's death (she isnt really) is too emotionally dead to cry, instead a shard of glass cuts his cheek and the trickle of blood serves the purpose.

Tengen Toppa Gurren Lagann has a version of it, particularly in the second movie. After Kittan's Heroic Sacrifice. Simon goes on to kick ass and avenge him in the Super Galaxy Gurren Lagann while crying tears of blood. In the movie, the massive mecha is crying glowing tears of blood from BOTH faces.

Black Butler: The maidservant Hannah does this when her master Aloisstabs out her eye (for just looking at him!) in the first episode of the second season. She also does this in the second opening when the bandage covering her ruined eye comes loose.

Agni seems to do this when sad...but when he's crying tears of joy, the tears are normal.

The manga Emerging centers around a mysterious new disease spreading throughout Tokyo that causes infectious High-Pressure Blood to gout from a victim's every orifice. Before the infected reach that stage, however, they will first notice that their eyes are extremely blood-shot, followed by tears of blood as the disease progresses.

Played for Laughs in Yuru-Yuri; Chitose is told that she would be automatically lose a pillow fight if she has a nosebleed and Kyouko immediately tries to invoke a fantasy. Chitose holds in the nosebleed, but the blood instead comes out from her eyes.

Played for Laughs in Silver Spoon: Hachiken is so irritated by his big brother being so nonchalant about getting into Tokyo University, then casually dropping out, he cries bloody tears of RAGE, while biting his lip hard enough to draw even more blood.

Comic Books

The villain Misery from Image Comics sheds a tear of blood every time she uses her powers.

In Global Frequency, an alien thought-virus infects a group of people living in a housing block; each one of them begins to ooze blood from their eyes.

The "zombies" in Black Gas have completely black eyes and weep black tears.

The Corinthian in The Sandman sheds tears of blood when Morpheus dies. Of course, since the Corinthian is an incarnated nightmare with razor-toothed mouths where his eyes should be, and in a past life was a serial killer who ate his victims' eyeballs (this incarnation is apparently firmly on the side of good, but no less creepy), this is really an example of both flavors at once. That said, this is actually a touching moment.

Amedeo gets these too, in the second part of The Corinthian: Death In Venice. Because the mouths are growing in.

In Scare Tactics, the vampire Screamqueen cries these when she read Grossout's story about how he became a walking tumor.

Film

Le Chiffre, the villain in the 2006 James Bond film Casino Royale, suffers from haemolacria in one eye, causing him to weep blood when stressed.

Flavor two example: in X 2 X Men United, when Lady Deathstrike is killed by being injected with molten Adamantium, she weeps silvery tears before dying.

Possibly a subversion, as the Adamantium leaks out of other orifices as well.

Flavor two example: in Kill Bill, when Gogo Yubari is killed with a nail through the head, she cries blood.

Flavor two was also used in John Woo's The Killer for two major scenes: one being the blinding-by-muzzle-flash of Jenny during the restaurant shootout that kicks off the plot, and the other being the death of the title character when he gets shot in the eyes by the main bad guy.

This trope is used in the movie One Hour Photo which, instead of being one of the two aforementioned flavours, is in fact distilled Nightmare Fuel.

The opening of Bram Stokers Dracula has Vlad, the title character, so crazy-angry at the death of his wife (since it was a suicide, which according to the religious doctrine of the age meant that she was damned) that he openly renounces God. He then takes his sword and stabs it into a stone cross, which bleeds. Then the statues in the chapel start crying blood. Then his candles start oozing blood. Then blood starts pouring out of the walls. Then Dracula drinks the blood and becomes a vampire. Narmtastic.

I Am Legend has people who are infected by the virus start to cry tears of blood. Then gain a craving for human flesh...

Marlena in Cloverfield oozes blood from her eyes, just as we learn how seriously screwed she is.

In Stargate, Ra's hand device, described as being able to melt bone, can cause its victims to bleed out the eyes and nose.

The Mummy Tomb of the Dragon Emperor uses this when, after the Dragon Emperor and his army are transformed into terracotta statues by Zi Yuan's curse, they seem to start crying mud.

This happens to Marni in Repo! The Genetic Opera after Nathan unknowingly poisons her. Not so sure if Blind Mag counts for this

Literature

Authors and poets in the Heian era (for example, the Tale of Genji) were obsessed with this trope. "Crying tears of blood" in that time period was the melodramatic equivalent of modern English speakers "crying their eyes out," resulting in some romantic poems of the period reading a little differently these days.

'Oh, my darling, my sleeves are stained crimson with blood at the thought of you...' Ew.

A phrase the Japanese borrowed from China. In Classical Chinese (and occassionally nowadays) the phrase "tears of blood" is up there with "having your intestines and liver disintegrate inch-by-inch" for expressing romantic tragic love.

The character Icaris, a Khorne Berzerker from the Warhammer 40,000 short story Honour Among Feinds by Dylan Owen weeps blood constantly because his opponents won't get to worship Khorne, just die in his name.

Live Action TV

The Hands of Blue from Firefly use a futuristic device that causes ocular haemorrhaging and subsequent cessation of electrical activity in the brain. This device is used on Agent McGinnis and the Feds with nightmarish results in the episode "Ariel" after they admit that they have had verbal contact with River, whom they want to recapture.

They start to bleed from the nose and mouth, too. The device appears to kill by causing fatal internal haemorrhaging.

In Those Left Behind, the weapons used by the Hands are shown to be even more powerful, liquefying a man's entire body and leaving only a tattered husk of skin behind.

On NCIS, they receive a clue ahead of time from a serial killer, implying the next victim will cry tears of blood. He does. It's creepy.

In Supernatural, the first sign of Bloody Mary's presence is that her victims begin to bleed from the eyes.

A statue of the Virgin Mary also started to cry blood to mark the approach of the demon Alistair.

The Wonder Twins from Heroes have a weird joint power; the woman, when stressed, begins to ooze black tears of poison. Anyone within a certain radius also begins to ooze the tears, but unlike her they subsequently die. The only way to stop the "infection" and revive those who have not been infected for long is for her brother (who is unaffected) to hold her hands and calm her down, at which point the tears turn into regular water. At the start of season two they did this around eighty times an episode; eventually Maya learned to control it herself. This has resulted in many fans making unflattering comparisons to...

The X-Files had an alien virus made of black oil that could control its hosts. The infected were shown to have black oil swirling on their eyes and would sometimes weep it too.

In the Doctor Who episode "Doomsday", a character who had been converted into a Cyberman cries oily tears as she turns on the rest of the Cybermen with a weapon that can kill them, meanwhile repeating the last thing she said before being converted.

Merlyn Temple of American Gothic cries these, or at least her body does, during a lovely guilt-inducing vision which haunts the coroner of Trinity—since he was complicit in covering up Sheriff Buck's crime of "mercy killing" her. The accompanying Madness Mantra on the tape recorder, both as an artificially deep Voice of the Legion and a freakily speeded-up version, is the icing on the cake for this very disturbing scene. (You know the villain of a piece must be awful if this is the sort of thing the good guys do regularly to combat his plots.)

Someone's at the Door.

In Andromeda Beka once got these from overdosing on Flash, a highly addictive stimulant taken as eye drops.

Music

Ayumi Hamasaki's Brillante music video features this.

Grave Digger has song with the exact title and theme on the Best of the Eighties compilation.

Unsurprisingly, the Blind Guardian song "Blood Tears" mentions just that. (It's about the torture of Maedhros from The Silmarillion- that particular detail is not in the book itself at all, though.)

Tabletop Games

Ravenloft (2nd edition) used to have a magic item that looked like a valuable coin. It could be used to trick merchants, but every time the owner used it this way, he would begin to shed tears of blood that terrified anyone viewing him. The amount of time the Tears of Blood persisted depended on how big an amount of money you stole. The coin was cursed and very hard to get rid of—it bonded once you used it in a single scam, even once.

Theatre

Video Games

Later in the game, Heavy Rain has this happen to Jayden because of his overuse of ARI to desperately trying to figure out who the Origami killer is. At first it's assumed that its the drug Jayden is taking as the cause, but its seen in one of the endings that ARI is just as addictive. For reference: Blood out of nose: It's the drug. Blood out of eyes: its the ARI.

A teaser trailer for House of the Dead Overkill has the announcer saying that you'll "cry tears of blood from your own eyes!", or something similar.

Trailers for Resident Evil 5 show some poor guy being infected with something that makes him weep black, oily tears.

Flavour two example: In Phoenix Wright: Ace Attorney, the fifth case of the third game has Godot "crying" blood (which seeps out from a cut on his face) shortly before being found guilty of a crime and probably dying in prison.

First and foremost is the recurring villain Carmilla. She's been appearing since Simon's Quest, and while she doesn't personally cry tears of blood, she has a mask and a flying skull that do. For this reason, she's associated with one of the series' greatest musical themes, "Bloody Tears" (which also debuted in Simon's Quest); it's her theme in Judgment, for instance. Lords of Shadow gave all this history a Shout-Out in the narration:

"Poor, beautiful Carmilla... you will cry bloody tears before this night has ended."

Castlevania: Aria of Sorrow utilizes the villain-induced statuary variety in the castle's throne room, in which an enormous statue of a woman's face has cried a river of blood across much of the room, all in response to the presence of Graham Jones, who believes he is the reincarnation of Dracula. However, this may not in fact have anything at all to do with the villain's presence, since a statue that continually cries blood seems like something Count Dracula would have had installed in his throne room simply for decor.

There's a statue in the X68000 version of Castlevania (later ported as Castlevania Chronicles) that cries tears of blood that turn into invincible skeletons. "Bloody Tears" is played here too.

There are similar statues in Castlevania: Harmony of Dissonance in the Skeleton's Den that also produce Blood Skeletons with their tears.

And in Castlevania: Portrait of Ruin there's a quest that requires fetching some holy water, which you get from a crying statue.

A statue that cries blood is also seen in one room in Castlevania 64. The blood turns into a blood monster.

The first use of "Bloody Tears" in a Castlevania game appears in the 1988 arcade game Haunted Castle. Dracula keeps a big painting of a blonde woman that weeps blood when Simon goes near it. This is possibly the origin of the song's name.

The Tears Of Lhys from Planescape: Torment were wept by the Mercykiller Lhys (naturally), falsely condemned for a crime and tortured to death; his innocence was only discovered after the fact. He wept exactly twelve tears of blood before dying. These became minor artifacts, and could be used by the character to permanently enhance one's Constitution score.

Also, the Nameless One weeps bloody tears after reliving an evil moment where one of his previous incarnations lured a girl to her death by pretending to be in love with her.

The Sorrow, from Metal Gear Solid 3, cried tears of blood before and after his confrontation with Snake. It should be noted he is a ghost.

who was shot in the eye he "cries" out of by the Boss.

Solving one of the puzzles in Devil May Cry 3 results in two statues joining a third in weeping tears of blood.

Zero and Zero Two from Kirby's Dreamland 3 and Kirby 64 respectively. The former even attacks using this method.

The final boss of Skies of Arcadia has a special attack which starts with bloody tears coming down from his eyes.

Towards the end of Silent Hill 1, during a confrontation with Harry in which Lisa Garland discovers that she is not actually human but the same as the other demonic nurses created by Alessa's nightmares, a cutscene shows her weeping blood before it begins to just ooze out from her skin.

The original readme(and subsequent instruction manuals) of Doom read "Some of the ceilings in DOOM can smash you, making you cry blood."

In Daggerfall, being infected with vampirism (a .06% chance every time you get hit by a vampire (who, by the way, are obnoxiously powerful)) causes you to have a dream the next time you sleep in which a beautiful woman cries tears of blood.

The intro movie for the fifth chapter in Phantasmagoria shows Adrienne lying on her bed when suddenly tears of blood start streaming down her cheeks. It turns out to be a bad dream.

Webcomics

Zimmy of Gunnerkrigg Court has her eyes completely obscured by black gunk, until the next rain washes it away—that's how we know she got red eyes. She's considered technically human, though with some weird... issues. Either way, it looks creepy.

In The Adventures of Dr. McNinja, Dan McNinja claims that he can store poison in his eyes and "shoot it out later like a toad" (a reference to the horned toad mentioned above). Turns out he isn't exaggerating.

Not completely sure this belongs here, but Dan also caused someone to pee blood. He'd run out of urine, but was so terrified that his body continued to pee anyway.

In the Oblivion-based online interactive story PREQUEL, Katia Managan has the natural Khajiit ability of darkvision. At least twice in the story, she activates it when heading into a dark place, then forgets to deactivate it when she turns back into the sun. She bleeds from her eyes a bit afterwards.

Web Original

Ayla and the Grinch in the Whateley Universe. Phase is fighting a demon and losing. He's beaten and broken, and lying at the feet base of the thing, and blood is dripping from his eye. Along with pretty much everywhere else. He gets rescued and healed.

In the world of YearZero, an anti-viral agent nicknamed "Copper" causes orange secretions in users. In the "Star Chamber" terrorism incident, a supposed government agent is seen "crying orange tears."

Western Animation

William Murderface, bassist for Dethklok in Metalocalypse cries tears of blood in the episode "Birthdayface," when the other members of the band get him a collection of priceless pieces of American history, specifically for him to destroy as he sees fit.

In the Family Guy episode "Patriot Games" when Stewie smashes a glass over Brian's head blood starts dripping from his eyes.

Real Life

Haemolacria is a physical condition in which blood is found in tears; this can be anything from a small trace to flows of red.

Stretching the definition a little bit, but the horned lizard (also known as the "horny toad") can squirt blood from its eyes up to a distance of three feet to ward off predators.

There are claims that some statues of the Virgin Mary (and statues of others, but almost exclusively Mary) have wept skim milk, blood and other substances in a miraculous fashion. Skeptics claim that the phenomenon can be attributed to condensation, group suggestion or hoaxes.

Jacinta Marto, one of the three kids who saw visions of the Virgin Mary at Fatima, was also a horrifically Ill Girl (you do not want details) who died as per her own predictions at the age of eleven in a Lisbon hospital. During the hearings for her beatification, the nuns who prepared her for burial testified that they found tears of blood on her face.

At least one Ancient Greek temple used machinery to make statues of gods appear to weep blood.

Some people suffering from stigmata are said to weep tears of blood.

If a person suffers of extreme altitude sickness, their ocular tear conducts break and blood pours from them. By that time, though, the person is practically dead because of the chronic lack of oxygen.

In a very scary version of Truth in Television we have an upcoming[when?] episode of National Geographic, featuring this, where a girl spontaneously bleeds from her eyes, head, nose, and hands. There is no known reason for this.

Something like this occurs with hippopotamuses, except in this case, they sweat blood, or a substance that resembles blood.

Endometriosis is an unpleasant condition where the lining of the uterus shows up in places it's not supposed to, such as the body cavity. There was a woman who had a patch show up in her eye. Meaning she wept blood every month.